Translation:I am not sleeping, because it is daytime.
I asked the same question in the Duolingo Polish Learners Facebook group. Here was the response I got:
"Bo" i "ponieważ" are interchangeable. "Ponieważ" is a bit more formal.
"Dlatego" is slightly different. Together with "że" (in the phrase "dlatego, że") it means just "because", same as "bo" and "ponieważ". However, when it stands alone, it's more like "this is why".
Jem, bo jestem głodny. = I am eating because I am hungry.
Jem dlatego, że jestem głodny. = I am eating because I am hungry.
Jem, ponieważ jestem głodny. = I am eating because I am hungry.
Jestem głodny, dlatego jem. – I am hungry, that's why (or: therefore) I am eating.
Thanks! That is very helpful. From what I can tell, it seems like "dlatego, że" would literally be "therefore (or: for this reason), that" i.e. "I am eating for this reason: that I am hungry." Which is certainly awkward in English, but I personally find it really helpful to understand the literal meaning of more idiomatic phrases :)
To add to that, the tendency I've seen is that ponieważ seems more natural for matter-of-fact type statements (like this one), whereas Bo tends to show up in casual conversation a bit more naturally. Also, if you're using the Vocative case, Bo is the only one that sounds right.
I also suggest "since" which is interchangeable with "as" when it is a conjunction.